Using the inverse method to investigate flow models for mixed convection of annular finned tube heat exchanger

The inverse heat conduction method (IHCM) and three-dimensional (3D) computational fluid dynamic (CFD) in combination with Tm k are used to select the appropriate flow model and near-wall treatment for the mixed convection of the annular finned tube heat exchanger. Thus, the numerical results obtained by all k-e models and near-wall treatments are yielded for 4 m/s ≤ Va ≤ 5 m/s. First, IHCM combined with Tm k is applied to estimate h and Q values. The obtained estimates of h and Q are used as reference values for CFD. The results show that the Tk and h results obtained by the standard (STD) k-e model with the standard wall function (SWF) are closer to Tm k and the estimates of h than those by the realizable (REAL) and RNG k-e models with various wall functions for Va of 4e5 m/s. The h value obtained from the STD k-e model with SWF, Va = 5 m/s and S = 15 mm may be 1.14 times that of the RNG k-e model and 0.48 times that of the REAL k-e model. The h value of the RNG k-e model with SWF is about 1.6e1.7 times that with EWT for S = 5 mm and Va = 4 m/s and 5 m/s. These differences mean that the appropriate flow model needs to be varied with Va to obtain more accurate numerical results. The y of RNG and STD k-e models does not exceed 3. However, the y of the REAL k-e model exceeds 6. To our best knowledge, no studies have explored this issue and the present investigation tries to bridge this gap.